This study will examine the factors associated with the incidence of asthma in young school children in Anchorage, Alaska. The purpose of the study is to evaluate the relative weight of individual risk factors and the weight of environmental proximity to traffic as a risk factor associated with the incidence of asthma in children. The study is based on kindergarten and first grade children (1600+ students) in twelve neighborhood schools. The schools have been selected because they have a catchment area of contiguous neighborhoods with residents of varied socioeconomic status. These schools include some of the poorest residents in the city as well as a large number of middle to high-income residents. As part of the study plan, the catchment area of the schools will be mapped and traffic parameters on the roadways within the neighborhoods will be measured using pneumatic devices. Local demographic and economic factors for each neighborhood are available from the city planning office. Traffic parameters will be entered in a geographic mapping system. Summary parameters for each school will then be calculated. The primary assessment will involve a survey of the parents of the kindergarten and first-grade students in the same neighborhood schools to assess the asthma symptoms of the children, family risk factors, in-home factors related to individual risk of asthma, socioeconomic status and racial/ethnic identity. The survey will also indicate the length of time the child spends in this neighborhood on a daily basis as well as the number of years that the child has lived at this address. Each address will be mapped and the traffic parameters calculated within a buffer zone of each child's home. The primary definition of asthma will be based on weighted survey responses including a medical diagnosis of asthma, using asthma medication, or asthma symptoms without symptoms of upper respiratory infection. Multi-level regression analysis will used to analyse the survey data and individual traffic exposure. Using this approach will increase the power of the study to examine the relationship between proximity to traffic and the incidence of asthma in young children.